Input device, and control method and program therefor

ABSTRACT

A degree of approach of an object in positions of a detection surface is periodically detected by a sensor unit, a group of detection data items indicating a result of the detection is generated in every one of cycles. The group of detection data items generated in the sensor unit is acquired in every one of cycles by a detection data acquisition unit. In the error determination unit, it is determined in every one of cycles whether there is an error in the detection operation due to noise based on a degree of a temporal change and a degree of a positional change in the detection data. When it is determined by the error determination unit that there is an error in the detection operation of one cycle, a process of acquiring the detection data generated in the one cycle is skipped in the detection data acquisition unit.

CLAIM OF PRIORITY

This application claims benefit of Japanese Patent Application No.2014-238416 filed on Nov. 26, 2014, 2014-259520 filed on Dec. 22, 2014,and 2014-259521 filed on Dec. 22, 2014, which are hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an input device that inputs informationaccording to an approach state of an object using a change incapacitance or the like, and a control method and a program therefor,and more particularly, to an input device that inputs informationaccording to an operation of a finger, a pen, or the like in variousinformation devices such as a computer.

2. Description of the Related Art

Since a sensor that detects a change in capacitance can detect approachof an object (for example, a finger or a pen) with a simpleconfiguration, the sensor is widely used for user interface devices ofvarious electronic devices, such as touch pads of note type computers ortouch panels of smart phones.

In International Publication No. WO 2012/117437, a touch panel deviceincluding a touch panel unit in which a plurality of electrodes arearranged is described. A scan electrode is determined from among theplurality of electrodes of the touch panel unit, and the touch panelunit is operated for the determined scanning electrode. Accordingly, ameasurement value reflecting a change in capacitance of each electrodeis acquired, and it is detected whether the touch panel unit is touchedbased on the acquired measurement value.

However, since such an input device is configured to be able tosensitively detect an object approaching a detection surface of asensor, there is a problem in that the sensor is particularlysusceptible to electromagnetic noise from the outside. For example, inthe case of the above-described capacitive sensor, since a change incapacitance of an electrode caused by approach of an object is detectedas a change in a small amount of charge, there is a problem in thaterroneous detection of coordinates or a contact state of an objecteasily occurs due to an influence of noise.

SUMMARY OF THE INVENTION

The present invention provides an input device, and a control method anda program therefor capable of reducing an influence of detection errordue to noise.

A first aspect of the present invention relates to an input device thatinputs information according to a state of approach of an object to adetection surface. This input device includes: a sensor unit configuredto detect a degree of the approach of the object at each of a pluralityof positions of the detection surface and generate detection dataindicating a result of the detection for each of the plurality ofpositions; a sensor control unit configured to control the sensor unitso that the sensor unit performs a periodic detection operation ofgenerating the detection data in the plurality of positions in every oneof cycles; a detection data acquisition unit configured to acquire aplurality of detection data generated for the plurality of positions inevery one of cycles of the detection operation; and an errordetermination unit configured to determine, in every one of cycles,whether or not there is an error in the detection operation due to noisebased on a degree of a temporal change and a degree of a positionalchange in the detection data. When the error determination unitdetermines that there is an error in the detection operation in onecycle, the detection data acquisition unit skips a process of acquiringthe detection data generated in the one cycle.

According to the above configuration, a plurality of detection dataitems indicating a degree of approach of an object at a plurality ofpositions on the detection surface is periodically generated by thesensor unit. In every one of cycles of a periodic detection operation ofthe sensor unit, the plurality of detection data items generated for theplurality of positions is acquired by the detection data acquisitionunit. Further, in the error determination unit, it is determined inevery one of cycles whether or not there is an error in the detectionoperation due to noise based on the degree of the temporal change andthe degree of the positional change in the detection data. When it isdetermined by the error determination unit that there is an error in thedetection operation of one cycle, a process of acquiring the detectiondata generated in the one cycle is skipped in the detection dataacquisition unit.

Thus, it is accurately determined whether or not there is an error inthe detection operation due to noise based on the degree of the temporalchange and the degree of the positional change in the detection data.Further, since the process of acquiring the detection data generated inthe cycle in which it is determined that there is an error in thedetection operation due to noise is skipped, it is possible toeffectively reduce an influence of the detection error due to noise.

Preferably, the error determination unit may calculate an evaluationvalue according to a degree to which the degree of the temporal changein the detection data further changes according to a position in everyone of cycles of the detection operation, and determine that there is anerror in the detection operation when the calculated evaluation valuesatisfies a predetermined error determination condition.

In this case, the error determination unit may calculate, for at leastsome of the plurality of positions, the evaluation value according to adifference between temporal change amounts of the detection data in aplurality of successive cycles of the detection operation, thedifference being a difference between the temporal change amount at oneposition on the detection surface and the temporal change amount at aposition adjacent to the one position.

Preferably, the error determination unit may calculate an evaluationvalue according to a degree to which the degree of the positional changein the detection data temporally changes in every one of cycles of thedetection operation, and determine that there is an error in thedetection operation when the calculated evaluation value satisfies apredetermined error determination condition.

In this case, the error determination unit may calculate, for at leastsome of the plurality of positions, the evaluation value according to anamount by which a difference between the detection data in one positionof the detection surface and the detection data at a position adjacentto the one position changes in a plurality of successive cycles of thedetection operation.

Preferably, the error determination unit may compare a sum of theevaluation values calculated for at least some of the plurality ofpositions with a predetermined threshold value, and determine whether ornot there is an error in the detection operation according to a resultof the comparison.

Accordingly, a change in the detection data locally generated due tonoise can be easily recognized.

Preferably, the error determination unit may compare respectiveevaluation values calculated for at least some of the plurality ofpositions with a predetermined threshold value, and determine that thereis an error in the detection operation when the number of positionssatisfying a condition of a predetermined magnitude relationship reachesa predetermined number as a result of the comparison.

Accordingly, when only detection data of a very small region is greatlychanged due to noise, a determination as an error in the detectionoperation is difficult.

Preferably, the error determination unit may calculate, for at leastsome of the plurality of positions, a first evaluation value accordingto a difference between the detection data in one position of thedetection surface and the detection data at a position adjacent to theone position in every one of cycles of the detection operation, and asecond evaluation value according to a temporal change amount of thedetection data in two successive cycles of the detection operation, anddetermine that there is an error in the detection operation when thefirst evaluation value and the second evaluation value that arecalculated satisfy a predetermined error determination condition.

In this case, the error determination unit may determine whether or notthere is an error in the detection operation based on a result ofcomparing a sum of the first evaluation values calculated for at leastsome of the plurality of positions with a first threshold value, and aresult of comparing a sum of the second evaluation values calculated forat least some of the plurality of positions with a second thresholdvalue.

Alternatively, the error determination unit may determine that there isan error in the detection operation on the condition that the number ofpositions satisfying a condition of a predetermined magnituderelationship reaches a predetermined number in a result of comparing thefirst evaluation value calculated for each of at least some of theplurality of positions with a first threshold value and/or that thenumber of positions satisfying the condition of the predeterminedmagnitude relationship reaches the predetermined number in a result ofcomparing the second evaluation value calculated for each of at leastsome of the plurality of positions with a second threshold value.

A second aspect of the present invention relates to a method in which acomputer controls an input device that includes a sensor unit thatdetects a degree of approach of an object at a plurality of positions ofa detection surface and generates detection data indicating a result ofthe detection for each of the plurality of positions, and inputsinformation according to a state of the approach of the object to thedetection surface. The method of controlling an input device includingsteps of: controlling the sensor unit so that the sensor unit performs aperiodic detection operation of generating the detection data in theplurality of positions in every one of cycles; acquiring a plurality ofdetection data items generated for the plurality of positions in everyone of cycles of the detection operation; and determining, in every oneof cycles of the detection operation, whether or not there is an errorin the detection operation due to noise based on a degree of a temporalchange and a degree of a positional change in the detection data. Whenit is determined in the step of determining the error that there is anerror in the detection operation in one cycle, the step of acquiring thedetection data includes skipping a process of acquiring the detectiondata generated in the one cycle.

Preferably, the step of determining an error may include calculating anevaluation value according to a degree to which the degree of thetemporal change in the detection data further changes according to aposition in every one of cycles of the detection operation, anddetermining that there is an error in the detection operation when thecalculated evaluation value satisfies a predetermined errordetermination condition.

In this case, the step of determining an error may include calculating,for at least some of the plurality of positions, the evaluation valueaccording to a difference between temporal change amounts of thedetection data in a plurality of successive cycles of the detectionoperation, the difference being a difference between the temporal changeamount in one position of the detection surface and the temporal changeamount at a position adjacent to the one position.

Preferably, the step of determining an error may include calculating anevaluation value according to a degree to which the degree of thepositional change in the detection data temporally changes in every oneof cycles of the detection operation, and determining that there is anerror in the detection operation when the calculated evaluation valuesatisfies a predetermined error determination condition.

In this case, the step of determining an error may include calculating,for at least some of the plurality of positions, the evaluation valueaccording to an amount by which a difference between the detection datain one position of the detection surface and the detection data at aposition adjacent to the one position changes in a plurality ofsuccessive cycles of the detection operation.

Preferably, the step of determining an error may include comparing a sumof the evaluation values calculated for at least some of the pluralityof positions with a predetermined threshold value, and determiningwhether there is an error in the detection operation according to aresult of the comparison.

Preferably, the step of determining an error may include comparingrespective evaluation values calculated for at least some of theplurality of positions with a predetermined threshold value, anddetermining that there is an error in the detection operation when thenumber of positions satisfying a condition of a predetermined magnituderelationship reaches a predetermined number as a result of thecomparison.

Preferably, the step of determining an error may include calculating,for at least some of the plurality of positions, a first evaluationvalue according to a difference between the detection data in oneposition of the detection surface and the detection data at a positionadjacent to the one position in every one of cycles of the detectionoperation, and a second evaluation value according to a temporal changeamount of the detection data in two successive cycles of the detectionoperation, and determining that there is an error in the detectionoperation when the first evaluation value and the second evaluationvalue that are calculated satisfy a predetermined error determinationcondition.

A third aspect of the present invention relates to a program for causinga computer to execute the method of controlling the input deviceaccording to the second aspect of the present invention.

According to the present invention, it is possible to reduce aninfluence of a detection error due to noise.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating an example of a configuration of aninput device according to an embodiment of the present invention;

FIGS. 2A and 2B are diagrams illustrating an example of detection datagroups input from a sensor unit in every one of cycles of a detectionoperation. FIG. 2A illustrates a detection data group input in thelatest cycle. FIG. 2B illustrates a detection data group input in acycle immediately before the detection data group illustrated in FIG.2A.

FIGS. 3A and 3B are diagrams illustrating that a positional distributionof a temporal change amount of detection data is different between acase in which the positional distribution is due to noise and a case inwhich the positional distribution is due to approach of an object. FIG.3A illustrates a distribution of the temporal change amount of thedetection data appearing due to an influence of noise, and FIG. 3Billustrates a distribution of the temporal change amount of thedetection data appearing due to approach of an object.

FIG. 4 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain the input device according to a first embodiment.

FIG. 5 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain an input device according to a second embodiment.

FIG. 6 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain an input device according to a third embodiment.

FIG. 7 is a first flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain an input device according to a fourth embodiment.

FIG. 8 is a second flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain the input device according to the fourth embodiment.

FIG. 9 is a first flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain an input device according to a fifth embodiment.

FIG. 10 is a second flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain the input device according to the fifth embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

FIG. 1 is a diagram illustrating an example of a configuration of aninput device according to an embodiment of the present invention.

The input device illustrated in FIG. 1 includes a sensor unit 10, aprocessing unit 20, a storage unit 30, and an interface unit 40. Theinput device according to this embodiment is a device that inputsinformation according to an approach state by causing an object such asa finger or a pen to approach a detection surface on which a sensor isprovided. The “approach” in this specification includes both of beingclose in a contact state and being close in a non-contact state.

Sensor Unit 10

The sensor unit 10 detects a degree of approach of an object such as afinger or a pen at each of a plurality of detection positionsdistributed in a detection surface. For example, the sensor unit 10includes a sensor matrix 11 in which capacitive sensor elements(capacitors) 12 of which the capacitance changes according to theapproach of an object are formed in a matrix form, a detection datageneration unit 13 that generates detection data corresponding to thecapacitance of a capacitive sensor element 12, and a driving unit 14that applies a driving voltage to the capacitive sensor element 12.

The sensor matrix 11 includes a plurality of driving electrodes Lxextending in a vertical direction (Y direction), and a plurality ofdetection electrodes Ly extending in a horizontal direction (Xdirection). The plurality of driving electrodes Lx are arranged inparallel in the horizontal direction (X direction), and the plurality ofdetection electrodes Ly are arranged in parallel in the verticaldirection (Y direction). The plurality of driving electrodes Lx and theplurality of detection electrodes Ly intersect in a lattice form, andare insulated from each other. The capacitive sensor element 12 isformed near an intersection portion of the driving electrode Lx and thedetection electrode Ly. Further, in the example of FIG. 1, shapes of theelectrodes Lx and Ly are drawn in a strip shape, but may be any othershape (for example, a diamond pattern).

The driving unit 14 applies a driving voltage to each capacitive sensorelement 12 of the sensor matrix 11. Specifically, the driving unit 14sequentially selects one driving electrode Lx from among the pluralityof driving electrodes Lx under the control of the processing unit 20,and periodically changes a potential of the selected driving electrodeLx. A potential of the driving electrode Lx changes in a predeterminedrange, and thus, the driving voltage applied to the capacitive sensorelement 12 formed near the intersection point of this driving electrodeLx and the detection electrode Ly changes in a predetermined range, andthe capacitive sensor element 12 is charged or discharged.

The detection data generation unit 13 generates the detection dataaccording to charge transferred in each detection electrode Ly when thecapacitive sensor element 12 is charged or discharged due to the drivingunit 14 applying the driving voltage. In other words, the detection datageneration unit 13 samples the charge transferred in each detectionelectrode Ly at a timing synchronized with a periodic change in thedriving voltage of the driving unit 14, and generates the detection dataaccording to a result of the sampling.

For example, the detection data generation unit 13 includes acapacitance-to-voltage conversion circuit (CV conversion circuit) thatoutputs a voltage according to the capacitance of the capacitive sensorelement 12, and an analog-to-digital conversion circuit (AD conversioncircuit) that converts an output signal of the CV conversion circuitinto a digital signal and outputs the digital signal as detection data.

The CV conversion circuit samples the charge transferred in thedetection electrode Ly under control of the processing unit 20 each timethe driving voltage of the driving unit 14 periodically changes and thecapacitive sensor element 12 is charged or discharged. Specifically,each time a positive or negative charge is transferred in the detectionelectrode Ly, the CV conversion circuit transfers this charge or acharge proportional thereto to a capacitor for reference, and outputs asignal according to a voltage generated in the capacitor for reference.For example, the CV conversion circuit outputs a signal according to anintegrated value or an average value of the charge periodicallytransferred in the detection electrode Ly or a charge proportionalthereto. The AD conversion circuit converts the output signal of the CVconversion circuit into a digital signal in a predetermined period undercontrol of the processing unit 20, and outputs the digital signal asdetection data.

Further, while the sensor unit 10 shown in the above-described exampledetects approach of the object based on a change in the capacitance(mutual capacitance) generated between the electrodes Lx and Ly, thepresent invention is not limited thereto and the approach of the objectmay be detected using various other schemes. For example, the sensorunit 10 may adopt a scheme of detecting capacitance (self-capacitance)generated between the electrode and a ground due to the approach of theobject. In the case of a scheme of detecting the self-capacitance, adriving voltage is applied to the detection electrode. Further, thesensor unit 10 is not limited to a capacitance scheme, and may utilize,for example, a resistance film scheme or be of an electromagneticinduction type.

Processing Unit 20

The processing unit 20 is a circuit that controls an overall operationof the input device and includes, for example, a computer that performsprocessing according to instruction codes of a program stored in thestorage unit 30 or a logic circuit that realizes a specific function.All of the processing of the processing unit 20 may be realized by thecomputer and the program, or a part or all thereof may be realized by adedicated logic circuit.

In the example of FIG. 1, the processing unit 20 includes a sensorcontrol unit 21, a detection data acquisition unit 22, an errordetermination unit 23, and a detection data processing unit 24.

The sensor control unit 21 controls the sensor unit 10 so that thesensor unit 10 performs a periodic detection operation of generatingdetection data in a plurality of detection positions (capacitive sensorelements 12 of the sensor matrix 11) of a detection surface in every oneof cycles. Specifically, the sensor control unit 21 controls circuits ofthe driving unit 14 and the detection data generation unit 13 so thatselection of the driving electrode and generation of a pulse voltage inthe driving unit 14, and selection of the detection electrode andgeneration of detection data in the detection data generation unit 13are periodically performed at an appropriate timing.

The detection data acquisition unit 22 acquires a plurality of detectiondata items (detection data group) generated for the plurality ofdetection positions on the detection surface in every one of cycles ofthe detection operation of the sensor unit 10 from the sensor unit 10.However, the detection data acquisition unit 22 skips a process ofacquiring the detection data generated in the one cycle when the errordetermination unit 23 to be described below determines that there is anerror in the detection operation of one cycle.

For example, the detection data acquisition unit 22 receives thedetection data group from the sensor unit 10 in every one of cycles ofthe detection operation, and stores the detection data group as inputdata DI in the storage unit 30. The detection data acquisition unit 22stores the input data DI generated in the cycle in which the errordetermination unit 23 determines that there is no error, as the outputdata DO, in the storage unit 30. On the other hand, the detection dataacquisition unit 22 does not store the input data DI generated in thecycle in which it is determined that there is an error, as the outputdata DO, in the storage unit 30. At the cycle in which the output dataDO of the storage unit 30 is not updated due to error determination, forexample, the detection data group (output data DO) having the same valueas that at the previous cycle is regarded as being acquired, andprocessing in a block of a subsequent stage (for example, detection dataprocessing unit 24) is performed.

The error determination unit 23 determines, in every one of the cycles,whether or not there is an error in the detection operation due to noisebased on a degree of a temporal change and a degree of a positionalchange in the detection data generated in the sensor unit 10.

For example, the error determination unit 23 calculates an evaluationvalue E according to a degree to which the degree of a temporal changein the detection data further changes according to a position in everyone of cycles of the detection operation in the sensor unit 10, anddetermines that there is an error in the detection operation of thesensor unit 10 when the calculated evaluation value E satisfies apredetermined error determination condition.

Specifically, the error determination unit 23 calculates the evaluationvalue E according to a difference between temporal change amounts of thedetection data generated in a plurality of successive cycles.

Here, the “temporal change amount” is an amount of a change in thedetection data in the same detection position generated in a pluralityof successive cycles. For example, a difference between the detectiondata in two successive cycles or a value related to a magnitude of achange in the detection data in three or more successive cycles (forexample, a difference between a maximum value and a minimum value, adispersion, or a standard deviation) may be the “temporal changeamount”.

Further, a “difference between the temporal change amounts of thedetection data” is a difference between the temporal change amount atone detection position of the detection surface and the temporal changeamount at a detection position adjacent to the one detection position.The “adjacent detection position” may include only one detectionposition or may include a plurality of detection positions. When the“adjacent detection position” includes a plurality of detectionpositions, for example, a difference between the temporal change amountat one detection position and an average value of the temporal changeamounts at a plurality of detection positions adjacent to the onedetection position may be the “difference between the temporal changeamounts of the detection data”.

The error determination unit 23 calculates the evaluation value Eaccording to the “difference between the temporal change amounts of thedetection data” for at least some of the plurality of detectionpositions on the detection surface, and obtains a sum S of theevaluation values E. The error determination unit 23 compares the sum Sof the calculated evaluation values E with a predetermined thresholdvalue TH1, and determines whether or not there is an error in thedetection operation according to a result of the comparison.

For example, the error determination unit 23 calculates the evaluationvalue E using the detection data groups (input data DI and input dataOLD) input from the sensor unit 10 via the detection data acquisitionunit 22 in every one of cycles.

FIGS. 2A and 2B are diagrams illustrating an example of a detection datagroup (input data DI) input from the sensor unit 10 in every one ofcycles of the detection operation. FIG. 2A illustrates a detection datagroup (input data DI) input in the latest cycle, and FIG. 2B illustratesa detection data group (input data OLD) input in a cycle immediatelybefore the cycle of the input data DI.

The detection data groups (the input data DI and OLD) shown in theexample of FIGS. 2A and 2B form two-dimensional data in a matrix form.“DI [n] [m]” indicates a matrix element in an m-th row and an n-thcolumn in the input data DI, and “OLD [n] [m]” indicates a matrixelement in an m-th row and an n-th column in the input data OLD.

Each matrix element of the two-dimensional data indicates the detectiondata generated for each of M×N detection positions arranged in matrixform in the detection surface. When a row direction in a matrix-likearrangement of the detection positions is an X direction and a columndirection is a Y direction, a row number and a column number of thetwo-dimensional data indicate an X coordinate and a Y coordinate of thedetection position. That is, the element in the m-th row and the n-thcolumn in the two-dimensional data indicates detection data generatedfor a detection position (hereinafter referred to as “detection positionP(n, m)”) of which the X coordinate is “n” and the Y coordinate is “m”in the detection surface.

An evaluation value E(n, m) at the detection position P(n, m) isexpressed by, for example, the following equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 1} \rbrack \mspace{619mu}} & \; \\{{E( {n,m} )} = \{ {{\frac{{DI}}{t}( {{n + 1},m} )} - {\frac{{DI}}{t}( {n,m} )}} \}^{2}} & (1)\end{matrix}$

“dDI(n, m)/dt” in Equation (1) indicates a temporal change amount of thedetection data generated for the detection position P(n, m). Further,“dDI(n+1, m)/dt” indicates a temporal change amount of the detectiondata generated for a detection position P(n+1, m). The temporal changeamounts are expressed by, for example, equations below.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 2} \rbrack \mspace{574mu}} & \; \\{{\frac{{DI}}{t}( {{n + 1},m} )} = {{{{DI}\lbrack {n + 1} \rbrack}\lbrack m\rbrack} - {{{OLD}\lbrack {n + 1} \rbrack}\lbrack m\rbrack}}} & ( {2\text{-}1} ) \\{{\frac{{DI}}{t}( {n,m} )} = {{{{DI}\lbrack n\rbrack}\lbrack m\rbrack} - {{{OLD}\lbrack n\rbrack}\lbrack m\rbrack}}} & ( {2\text{-}2} )\end{matrix}$

The error determination unit 23 calculates a sum S of the evaluationvalues E(n, m) in the entire detection surface using, for example, thefollowing equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 3} \rbrack \mspace{619mu}} & \; \\{S = {\sum\limits_{m = 0}^{M - 1}\; {\sum\limits_{n = 0}^{N - 2}\; {E( {n,m} )}}}} & (3)\end{matrix}$

The error determination unit 23 determines that there is an error in thedetection operation due to noise when the sum S is greater than thepredetermined threshold value TH1.

The detection data processing unit 24 performs a process of calculatingcoordinates of a position that the object approaches, a process ofdetermining a type of the object, or the like, based on the output dataDO obtained in every one of cycles in the detection data acquisitionunit 22.

For example, the detection data processing unit 24 calculates adifference between the output data DO in a matrix form acquired by thedetection data acquisition unit 22 and a base value in a matrix formstored in another storage area (a base value memory) of the storage unit30 in advance, and stores a result of the calculation as two-dimensionaldata in a matrix form in the storage unit 30. A value (base value)serving as a reference for the detection data in a state in which theobject does not approach the detection surface is stored in the basevalue memory.

The detection data processing unit 24 specifies an object approachregion on the detection surface based on the two-dimensional dataindicating the amount of change from the base value, and calculatescoordinates of the object from, for example, a shape of the specifiedapproach region or a distribution of the data value in the approachregion. Further, the detection data processing unit 24 determineswhether the object comes in contact or a type (finger/palm) of theobject based on an area of the approach region in the detection surfaceof the object of which the coordinates have been calculated, magnitudesof the data values in the approach region, or the like.

Storage Unit 30

The storage unit 30 stores constant data or variable data that is usedfor processing in the processing unit 20. When the processing unit 20includes a computer, the storage unit 30 may store a program executed inthe computer. The storage unit 30 includes a volatile memory such as aDRAM or an SRAM, a nonvolatile memory such as a flash memory, a harddisk, or the like.

Interface Unit 40

The interface unit 40 is a circuit for exchanging data between the inputdevice and another control device (for example, a control IC of aninformation device having the input device mounted thereon). Theprocessing unit 20 outputs information (for example, coordinateinformation of the object or the number of objects) stored in thestorage unit 30 from the interface unit 40 to a control device (notshown). Further, the interface unit 40 may acquire a program to beexecuted in a computer of the processing unit 20 from a disk drivedevice (not shown) (a device that reads a program recorded in anon-transitory storage medium), a server, or the like, and load theprogram onto the storage unit 30.

Next, an error determination of a detection operation and acquisition ofdetection data according to this in the input device having the aboveconfiguration will be described.

FIGS. 3A and 3B are diagrams illustrating that a positional distributionof a temporal change amount of the detection data is different between acase in which the positional distribution is due to noise and a case inwhich the positional distribution is due to approach of an object. FIG.3A illustrates a distribution of the temporal change amount of thedetection data appearing due to an influence of noise, and FIG. 3Billustrates a distribution of the temporal change amount of thedetection data appearing due to approach of an object (for example, afinger).

When the detection data is changed due to the approach of the objectsuch as a finger, the temporal change amount of the detection data isrelatively small as illustrated in FIG. 3B, and a positional change ofthe temporal change amount appears relatively gradually. On the otherhand, when the detection data is changed due to an influence of noise,the temporal change amount of the detection data is large as illustratedin FIG. 3A, and the positional change of the temporal change amountappears suddenly.

Therefore, when the detection data is changed due to an influence ofnoise, the temporal change amounts as shown in Equations (2-1) and (2-2)increase and the evaluation value E(n, m) of Equation (1) obtained bysquaring the difference between the temporal change amounts increases.Accordingly, the sum S of Equation (3) in which the evaluation valuesE(n, m) are summed becomes a large value. Therefore, when the sum Sexceeds the predetermined threshold value TH1, it can be determined thatthere is an error in the detection operation due to noise.

FIG. 4 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain the input device according to the first embodiment.

ST100: When starting the operation, the processing unit 20 initializesthe input data DI and OLD and the output data DO stored in the storageunit 30.

ST110: The detection data acquisition unit 22 receives the detectiondata group corresponding to one cycle (N×M detection data correspondingto N×M detection positions in the detection surface) from the sensorunit 10, and stores this detection data group as the input data DI inthe storage unit 30.

ST120: The error determination unit 23 initializes “m” indicating a Ycoordinate of the detection position and “S” indicating a sum of theevaluation values E to zero.

ST130: The error determination unit 23 initializes “n” indicating anX-coordinate of the detection position to zero.

ST140: The error determination unit 23 calculates the evaluation valueE(n, m) at the detection position P(n, m) by referring to latest inputdata DI and previous input data OLD stored in the storage unit 30. Thecalculation of the evaluation value E based on the input data DI and theprevious input data OLD is not limited to the calculation of the squareas shown in Equation (1). For example, an absolute value may becalculated unlike the calculation of the square in Equation (1), orone-half power (square root) or the fourth power may be calculated.

ST150: The error determination unit 23 adds the evaluation value E(n, m)calculated in step ST140 to the sum S.

ST240 and ST250: The error determination unit 23 adds “1” to “n”indicating the X-coordinate of the detection position and determineswhether “n” is equal to or greater than “N−1”. When “n” is smaller than“N−1”, the error determination unit 23 returns to step ST140 to repeatthe calculation of the evaluation value E(n, m) and the updating of thesum S described above. When “n” is equal to or greater than “N−1”, theerror determination unit 23 proceeds to step ST310.

ST310 and ST320: The error determination unit 23 adds “1” to “m”indicating the Y coordinate of the detection position, and determineswhether “m” is equal to or greater than “M”. When “m” is smaller than“M”, the error determination unit 23 returns to step ST130 to repeat theprocess of steps ST130 to ST250. When “m” is equal to or greater than“M”, the error determination unit 23 proceeds to next step ST330.

ST330: The error determination unit 23 compares the sum S that is aresult of summing all the evaluation values E of the detection surfacewith a threshold value TH1. When the sum S is smaller than the thresholdvalue TH1, the error determination unit 23 determines that there is noerror in the detection operation of the sensor unit 10. When the sum Sis equal to or greater than the threshold value TH1, the errordetermination unit 23 determines that there is an error in the detectionoperation.

ST350: When the error determination unit 23 determines that there is noerror, the detection data acquisition unit 22 sets the input data DIinput from the sensor unit 10 in the latest cycle as the output data DO,and stores the output data DO in the storage unit 30 (detection dataacquisition process). On the other hand, when the error determinationunit 23 determines that there is an error, the detection dataacquisition unit 22 skips this detection data acquisition process. In acycle in which the detection data acquisition process is skipped, theoutput data DO stored in the storage unit 30 is not updated.

ST360: The error determination unit 23 applies the input data DI storedin the storage unit 30 to the input data OLD, and returns to step ST110.Accordingly, the input data DI of the latest cycle is stored in thestorage unit 30 as the input data OLD of the previous cycle, and thenthe input data DI is updated to the latest value.

As described above, according to the input device of this embodiment, itis possible to accurately determine whether or not there is an error inthe detection operation due to noise based on a degree of the temporalchange and a degree of the positional change in the detection data.Further, since the process of acquiring the detection data generated ina cycle in which it is determined that there is an error in thedetection operation due to noise is skipped, it is possible to preventcalculation of the coordinates or the like from being performed based onwrong detection data, and to effectively reduce an influence of thedetection error due to noise.

Further, according to the input device of this embodiment, since it isdetermined whether or not there is an error in the detection operationbased on the sum S obtained by summing the evaluation values E in therespective detection positions on the detection surface, it is easy torecognize a change in the detection data locally occurring due to aninfluence of noise, and it is possible to determine whether or not thereis an error more accurately.

Second Embodiment

Next, a second embodiment of the present invention will be described.

An input device according to the second embodiment is obtained bychanging the determination operation of the error determination unit 23in the input device according to the first embodiment. Otherconfigurations are the same as those of the input device according tothe first embodiment.

The error determination unit 23 in the second embodiment calculates anevaluation value EA according to a degree to which a degree of thepositional change in the detection data temporally changes in every oneof cycles of the detection operation of the sensor unit 10. When theevaluation value EA satisfies a predetermined error determinationcondition, the error determination unit 23 determines that there is anerror in the detection operation of the sensor unit 10.

Specifically, the error determination unit 23 calculates the evaluationvalue EA according to an amount by which the positional change amount ofthe detection data has temporally changed in a plurality of successivecycles of the detection operation.

Here, the “positional change amount” is a difference between thedetection data in one position of the detection surface and thedetection data at a position adjacent to the one position. The “adjacentdetection position” may include only one detection position or mayinclude a plurality of detection positions. When the “adjacent detectionposition” includes a plurality of detection positions, for example, adifference between detection data at one detection position and anaverage value of detection data at a plurality of detection positionsadjacent to the one detection position may be the “positional changeamount”.

Further, the “amount by which the positional change amount hastemporally changed” is an amount by which the positional change amountfor the same detection position has changed in a plurality of successivecycles. For example, a difference between the positional change amountsin two successive cycles or a value related to a magnitude of a changein the positional change amount in three or more successive cycles (forexample, a difference between a maximum value and a minimum value, adispersion, or a standard deviation) may be the “amount by which thepositional change amount of the detection data has temporally changed”.

The error determination unit 23 calculates an evaluation value EAaccording to the “amount by which the positional change amount hastemporally changed” for at least some of a plurality of detectionpositions on the detection surface, and obtains a sum SA of theevaluation values EA. The error determination unit 23 compares the sumSA of the calculated evaluation values EA with a predetermined thresholdvalue TH1, and determines whether or not there is an error in thedetection operation according to a result of the comparison.

An evaluation value EA(n, m) in a detection position P(n, m) isexpressed by, for example, the following equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 4} \rbrack \mspace{619mu}} & \; \\{{{EA}( {n,m} )} = \{ {{\frac{{DI}}{x}( {n,m} )} - {\frac{{OLD}}{x}( {n,m} )}} \}^{2}} & (4)\end{matrix}$

“dDI(n, m)/dx” in Equation (4) indicates a positional change amount ofthe detection data of the input data DI calculated for the detectionposition P(n, m). Further, “dOLD (n, m)/dx” indicates a positionalchange amount of the detection data of the input data OLD calculated forthe detection position P(n, m). The positional change amount isexpressed by, for example, the following equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 5} \rbrack \mspace{574mu}} & \; \\{{\frac{{DI}}{t}( {n,m} )} = {{{{DI}\lbrack {n + 1} \rbrack}\lbrack m\rbrack} - {{{DI}\lbrack n\rbrack}\lbrack m\rbrack}}} & (5) \\{{\frac{{OLD}}{t}( {n,m} )} = {{{{OLD}\lbrack {n + 1} \rbrack}\lbrack m\rbrack} - {{{OLD}\lbrack n\rbrack}\lbrack m\rbrack}}} & (5)\end{matrix}$

The error determination unit 23 calculates the sum SA of the evaluationvalues EA(n, m) in the entire detection surface using, for example, thefollowing equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 6} \rbrack \mspace{619mu}} & \; \\{{SA} = {\sum\limits_{m = 0}^{M - 1}\; {\sum\limits_{n = 0}^{N - 2}\; {{EA}( {n,m} )}}}} & (6)\end{matrix}$

When this sum SA is greater than a predetermined threshold value TH1,the error determination unit 23 determines that there is an error in thedetection operation due to noise.

FIG. 5 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection datain the input device according to a second embodiment. The flowchartillustrated in FIG. 5 is obtained by changing step ST120 in theflowchart illustrated in FIG. 4 to step ST120A, steps ST140 and ST150 tosteps ST140A and ST150A, and step ST330 to step ST330A. Other steps arethe same as those in the flowchart illustrated in FIG. 4. Here, only thechanged steps will be described.

ST120A: The error determination unit 23 initializes “m” indicating a Ycoordinate of the detection position and “SA” indicating a sum of theevaluation values EA to zero.

ST140A: The error determination unit 23 calculates an evaluation valueEA(n, m) in a detection position P(n, m) by referring to latest inputdata DI and previous input data OLD stored in the storage unit 30.

ST150A: The error determination unit 23 adds the evaluation values EA(n,m) calculated in step ST140A to the sum SA.

ST330A: The error determination unit 23 compares the sum SA that is aresult of summing all evaluation values EA of the detection surface witha threshold value TH1. When the sum SA is smaller than the thresholdvalue TH1, the error determination unit 23 determines that there is noerror in the detection operation of the sensor unit 10. When the sum SAis greater than the threshold value TH1, the error determination unit 23determines that there is an error in the detection operation.

In the input device according to the second embodiment described above,it is possible to achieve the same effect as that of the input deviceaccording to the first embodiment. That is, it is possible to accuratelydetermine whether or not there is an error in the detection operationdue to noise based on a degree of the temporal change in the detectiondata and a degree of the positional change in the detection data.Further, since the process of acquiring the detection data generated ina cycle in which it is determined that there is an error in thedetection operation due to noise is skipped, it is possible toeffectively reduce an influence of the detection error due to noise.

Third Embodiment

Next, a third embodiment of the present invention will be described.

The input device according to the third embodiment is obtained bychanging the determination operation of the error determination unit 23in the input device according to the first embodiment. Otherconfigurations are the same as those of the input device according tothe first embodiment.

The error determination unit 23 in the third embodiment calculates theevaluation value E (for example, Equation (1)) indicating the degree ofthe temporal change and the degree of the positional change in thedetection data for at least some of the plurality of detection positionsin the detection surface, and compares each calculated evaluation valueE with a predetermined threshold value TH2. The error determination unit23 counts the number “K” of detection positions in which a result of thecomparison satisfies a condition of a predetermined magnituderelationship (for example, “E≧TH2”), and determines that there is anerror in the detection operation when the count value K reaches apredetermined threshold value TH3.

FIG. 6 is a flowchart illustrating a process related to an errordetermination of a detection operation and acquisition of detection dataof the input device according to the third embodiment. The flowchartillustrated in FIG. 6 is obtained by changing step ST120 in theflowchart illustrated in FIG. 4 to step ST120B, replacing step ST150with steps ST160 and ST170, and replacing step ST330 with step ST340.The other steps are the same as those of the flowchart illustrated inFIG. 4. Here, only the changed or replaced steps will be described.

ST120B: The error determination unit 23 initializes “m” indicating the Ycoordinate of the detection position and the count value K to zero.

ST160 and ST170: The error determination unit 23 compares an evaluationvalue E calculated in step ST140 with a threshold value TH2, and adds“1” to the count value K when the evaluation value E is greater than thethreshold value TH2. When the evaluation value E is smaller than thethreshold value TH2, the error determination unit 23 maintains the countvalue K.

ST340: The error determination unit 23 compares the count value K thatis the number of the detection positions in which the evaluation value Eis greater than the threshold value TH2, with a predetermined thresholdvalue TH3. When the count value K is smaller than the threshold valueTH3, the error determination unit 23 determines that there is no errorin the detection operation of the sensor unit 10. When the count value Kis greater than the threshold value TH3, the error determination unit 23determines that there is an error in the detection operation.

While the error determination unit 23 compares the evaluation value E inEquation (1) with the threshold value TH2 in the example of theflowchart described above, the error determination unit 23 may comparethe evaluation value EA of Equation (4) rather than the evaluation valueE with the threshold value TH2.

In the input device according to the third embodiment described above,it is also possible to achieve the same effect as that of the inputdevice according to the first embodiment. That is, it is possible toaccurately determine whether or not there is an error in the detectionoperation due to noise based on a degree of the temporal change in thedetection data and a degree of the positional change in the detectiondata. Further, since the process of acquiring the detection datagenerated in a cycle in which it is determined that there is an error inthe detection operation due to noise is skipped, it is possible toeffectively reduce an influence of the detection error due to noise.

Further, in the input device according to this embodiment, even when theevaluation value E or the evaluation value EA becomes locally extremelylarge value due to noise, if a region thereof is very small, it ispossible to prevent the error from being determined as an error in thedetection operation of the entire detection surface. An error in thedetection data generated in a very small region is likely to be removedthrough a subsequent filter process. Accordingly, in this case, bypreventing the error from being determined as an error in the detectionoperation of the entire detection surface, it is possible to suppressdeterioration of object detection performance due to temporary stoppingof the detection data acquisition process.

Fourth Embodiment

Next, a fourth embodiment of the present invention will be described.

An input device according to the fourth embodiment is different from theinput device according to the first embodiment in the determinationoperation of the error determination unit 23. Other configurations arethe same as those of the input device according to the first embodiment.

The error determination unit 23 in the fourth embodiment calculates afirst evaluation value E1 according to a positional change amount of thedetection data and a second evaluation value E2 according to a temporalchange amount of the detection data for at least some of a plurality ofdetection positions in the detection surface, and determines that thereis an error in the detection operation of the sensor unit 10 when thefirst evaluation value E1 and the second evaluation value E2 that havebeen calculated satisfy a predetermined error determination condition.

Here, the “positional change amount” is a difference between thedetection data in one position of the detection surface and thedetection data at a position adjacent to the one position. The “adjacentdetection position” may include only one detection position or mayinclude a plurality of detection positions. When the “adjacent detectionposition” includes a plurality of detection positions, for example, adifference between detection data at one detection position and anaverage value of detection data at a plurality of detection positionsadjacent to the one detection position may be the “positional changeamount”.

Further, the “temporal change amount” is an amount of a change in thedetection data in the same detection position generated in a pluralityof successive cycles. For example, a difference between the detectiondata in two successive cycles or a value related to a magnitude of achange in the detection data in three or more successive cycles (forexample, a difference between a maximum value and a minimum value, adispersion, or a standard deviation) may be the “temporal changeamount”.

The first evaluation value E1 according to the “positional changeamount” at the detection position P(n, m) is expressed by, for example,the following equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 7} \rbrack \mspace{619mu}} & \; \\{{E\; 1( {n,m} )} = {\{ {\frac{{DI}}{x}( {n,m} )} \}^{2} = \{ {{{{DI}\lbrack {n + 1} \rbrack}\lbrack m\rbrack} - {{{DI}\lbrack n\rbrack}\lbrack m\rbrack}} \}^{2}}} & (7)\end{matrix}$

Further, the second evaluation value E2 according to the “temporalchange amount” at the detection position P(n, m) is expressed by, forexample, the following equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 8} \rbrack \mspace{619mu}} & \; \\{{E\; 2( {n,m} )} = {\{ {\frac{{DI}}{x}( {n,m} )} \}^{2} = \{ {{{{DI}\lbrack n\rbrack}\lbrack m\rbrack} - {{{OLD}\lbrack n\rbrack}\lbrack m\rbrack}} \}^{2}}} & (8)\end{matrix}$

The error determination unit 23 calculates a sum S1 of the firstevaluation values E1(n, m) and a sum S2 of the second evaluation valuesE2(n, m) in the entire detection surface using, for example, thefollowing equation.

$\begin{matrix}{\lbrack {{Equation}\mspace{14mu} 9} \rbrack \mspace{574mu}} & \; \\{{S\; 1} = {\sum\limits_{m = 0}^{M - 1}\; {\sum\limits_{n = 0}^{N - 2}\; {E\; 1( {n,m} )}}}} & ( {9\text{-}1} ) \\{{S\; 2} = {\sum\limits_{m = 0}^{M - 1}\; {\sum\limits_{n = 0}^{N - 2}\; {E\; 2( {n,m} )}}}} & ( {9\text{-}2} )\end{matrix}$

When this sum S1 is greater than a predetermined threshold value TH4 andthe sum S2 is greater than a predetermined threshold value TH5, theerror determination unit 23 determines that there is an error in thedetection operation due to noise.

FIGS. 7 and 8 are flowcharts illustrating a process related to an errordetermination of the detection operation and acquisition of thedetection data in the input device according to the fourth embodiment.The flowcharts illustrated in FIGS. 7 and 8 are obtained by changingstep ST120 in the flowchart illustrated in FIG. 4 to step ST120C,replacing step ST140 with steps ST140C and ST140D, replacing step ST150with steps ST150C and ST150D, and changing step ST330 to step ST330C.Other steps are the same as those of the flowchart illustrated in FIG.4. Here, only the changed or replaced steps will be described.

ST120C: The error determination unit 23 initializes “m” indicating a Ycoordinate of the detection position, “S1” indicating a sum of the firstevaluation values E1, and “S2” indicating the sum of the secondevaluation values E2 to zero.

ST140C and ST140D: The error determination unit 23 calculates the firstevaluation value E1 (n, m) and the second evaluation value E2(n, m) atthe detection position P(n, m) by referring to the latest input data DIand the previous input data OLD stored in the storage unit 30.

ST150C and ST150D: The error determination unit 23 adds the firstevaluation value E1(n, m) calculated in step ST140C to the sum S1, andadds the second evaluation value E2(n, m) calculated in step ST140D tothe sum S2.

ST330C: The error determination unit 23 compares the sum S1 that is aresult of summing the first evaluation values E1 of the entire detectionsurface with the threshold value TH4, and compares the sum S2 that is aresult of summing the second evaluation values E2 of the entiredetection surface with the threshold value TH5. When the sum S1 issmaller than the threshold value TH4 and the sum S2 is smaller than thethreshold value TH5, the error determination unit 23 determines thatthere is no error in the detection operation of the sensor unit 10. Onthe other hand, when the sum S1 is greater than the threshold value TH4or the sum S2 is greater than the threshold value TH5, the errordetermination unit 23 determines that there is an error in the detectionoperation.

In another modification example, the error determination unit 23 maydetermine that there is no error in the detection operation of thesensor unit 10 when the sum S1 is smaller than the threshold value TH4or the sum S2 is smaller than the threshold value TH5, and determinethat there is an error in the detection operation of the sensor unit 10when the sum S1 is greater than the threshold value TH4 and the sum S2is greater than the threshold value TH5.

In the input device according to the fourth embodiment described above,it is also possible to achieve the same effect as that of the inputdevice according to the first embodiment. That is, it is possible toaccurately determine whether or not there is an error in the detectionoperation due to noise based on a degree of the temporal change in thedetection data and a degree of the positional change in the detectiondata. Further, since the process of acquiring the detection datagenerated in a cycle in which it is determined that there is an error inthe detection operation due to noise is skipped, it is possible toeffectively reduce an influence of the detection error due to noise.

Fifth Embodiment

Next, a fifth embodiment of the present invention will be described.

An input device according to the fifth embodiment is different from theinput device according to the first embodiment in the determinationoperation of the error determination unit 23. Other configurations arethe same as those of the input device according to the first embodiment.

The error determination unit 23 in the fifth embodiment calculates afirst evaluation value E1 (for example, Equation (7)) according to apositional change amount of detection data, and a second evaluationvalue E2 (for example, Equation (8)) according to a temporal changeamount of the detection data for at least some of a plurality ofdetection positions in a detection surface.

The error determination unit 23 compares each calculated, firstevaluation value E1 with a predetermined threshold value TH6 and countsthe number “K1” of detection positions satisfying a predeterminedmagnitude relationship (for example, “E1≧TH6”) as a result of thecomparison. Further, the error determination unit 23 compares eachcalculated, second evaluation value E2 with a predetermined thresholdvalue TH7 and counts the number “K2” of detection positions satisfying apredetermined magnitude relationship (for example, “E2≧TH7”) as a resultof the comparison.

The error determination unit 23 determines that there is an error in thedetection operation when the count value K1 reaches a predeterminedthreshold value TH8 and the count value K2 reaches a predeterminedthreshold value TH9.

FIGS. 9 and 10 are flowcharts illustrating a process related to an errordetermination of the detection operation and acquisition of thedetection data in the input device according to the fifth embodiment.The flowcharts illustrated in FIGS. 9 and 10 are obtained by changingstep ST120C in the flowcharts illustrated in FIGS. 7 and 8 describedabove to step ST120E, replacing step ST150C with steps ST160E andST170E, replacing step ST150D with steps ST160F and ST170F, andreplacing step ST330C into step ST340E. Other steps are the same asthose of the flowcharts illustrated in FIGS. 7 and 8. Here, only thechanged or replaced steps will be described.

ST120E: The error determination unit 23 initializes “m” indicating the Ycoordinate of the detection position and the count values K1 and K2 tozero.

ST160E and ST170E: The error determination unit 23 compares the firstevaluation value E1 calculated in step ST140C with the threshold valueTH6, and adds “1” to the count value K1 when the first evaluation valueE1 is greater than the threshold value TH6. When the first evaluationvalue E1 is smaller than the threshold value TH6, the errordetermination unit 23 maintains the value of the count value K1.

ST160F and ST170F: The error determination unit 23 compares the secondevaluation value E2 calculated in step ST140D with the threshold valueTH7, and adds “1” to the count value K2 when the second evaluation valueE2 is greater than the threshold value TH7. When the second evaluationvalue E2 is smaller than the threshold value TH7, the errordetermination unit 23 maintains the value of the count value K2.

ST340E: The error determination unit 23 compares the count value K1 thatis the number of detection positions in which the first evaluation valueE1 is greater with the threshold value TH6 with the predeterminedthreshold value TH8, and compares the count value K2 that is the numberof detection positions in which the second evaluation value E2 isgreater with the threshold value TH7 with the predetermined thresholdvalue TH9. When the count value K1 is smaller than the threshold valueTH8 and the count value K2 is smaller than the threshold value TH9, theerror determination unit 23 determines that there is no error in thedetection operation of the sensor unit 10. When the count value K1 isgreater than the threshold value TH8 or the count value K2 is greaterthan the threshold value TH9, the error determination unit 23 determinesthat there is an error in the detection operation.

In another modification example, the error determination unit 23 maydetermine that there is no error in the detection operation of thesensor unit 10 when the count value K1 is smaller than the thresholdvalue TH8 or the count value K2 is smaller than the threshold value TH9,and determine that there is an error in the detection operation of thesensor unit 10 when the count value K1 is greater than the thresholdvalue TH8 and the count value K2 is greater than the threshold valueTH9.

In the input device according to the fifth embodiment described above,it is also possible to achieve the same effect as that of the inputdevice according to the first embodiment. That is, it is possible toaccurately determine whether or not there is an error in the detectionoperation due to noise based on a degree of the temporal change in thedetection data and a degree of the positional change in the detectiondata. Further, since the process of acquiring the detection datagenerated in a cycle in which it is determined that there is an error inthe detection operation due to noise is skipped, it is possible toeffectively reduce an influence of the detection error due to noise.

While various embodiments of the present invention have been describedabove, the present invention is not limited to only the above-describedembodiments and includes various variations.

For example, each processing block of the processing unit 20 in eachembodiment described above may be configured using a computer and aprogram or may be configured using dedicated hardware.

Further, while the “positional change amount of the detection data” usedfor calculation of the evaluation value in the error determination unit23 of each embodiment described above is an amount of a change in onlythe X direction, this positional change amount may be an amount of achange in only the Y direction, or may be an amount of change for bothof the X direction and the Y direction (or multiple directions includingthree or more directions).

The input device of the embodiment of the present invention is notlimited to a user interface device that inputs information using anoperation of a finger or the like. That is, the input device of theembodiment of the present invention can be widely applied to devicesthat input information according to approach of various objects notlimited to a human body to the detection surface.

It should be understood by those skilled in the art that variousmodifications, combinations, sub-combinations and alterations may occurdepending on design requirements and other factors insofar as they arewithin the scope of the appended claims or the equivalents thereof.

1. An input device for inputting information according to a state ofapproach of an object thereto, the input device comprising: a detectionsurface to which the object approaches; a sensor unit configured todetect a degree of the approach of the object at each of a plurality ofpositions of the detection surface, and to generate detection dataindicating a result of the detection for each of the plurality ofpositions; a sensor control unit configured to control the sensor unitsuch that the sensor unit periodically performs a detection operationonce in each cycle to generate the detection data for the plurality ofpositions; a detection data acquisition unit configured to acquire oncein each cycle the detection data for the plurality of positionsgenerated in the detection operation; and an error determination unitconfigured to determine, in each cycle, whether or not an error hasoccurred in the detection operation due to noise based on a degree of atemporal change and a degree of a positional change in the detectiondata, wherein the detection data acquisition unit skips a process ofacquiring the detection data for a current cycle if the errordetermination unit determines that an error has occurred in thedetection operation in the current cycle.
 2. The input device accordingto claim 1, wherein the error determination unit is further configuredto calculate an evaluation value according to a degree of a positionalchange in the degree of the temporal change in the detection data ineach cycle, and determines that an error has occurred in the detectionoperation if the calculated evaluation value satisfies a predeterminederror determination condition.
 3. The input device according to claim 2,wherein the error determination unit calculates, for at least some ofthe plurality of positions, the evaluation value based on the positionalchange obtained from a difference between the temporal change in thedetection data at a first position among the at least some of theplurality of positions and the temporal change in the detection data ata second position adjacent to the first position, the temporal changebeing obtained from the detection data in a plurality of successivecycles.
 4. The input device according to claim 1, wherein the errordetermination unit is further configured to calculate an evaluationvalue according to a degree of a temporal change in the degree of thepositional change in the detection data in each cycle, and determinesthat an error has occurred in the detection operation if the calculatedevaluation value satisfies a predetermined error determinationcondition.
 5. The input device according to claim 4, wherein the errordetermination unit calculates, for at least some of the plurality ofpositions, the evaluation value based on the temporal change in adifference between the detection data at a first position among the atleast some of the plurality of positions and the detection data at asecond position adjacent to the first position, the temporal changebeing obtained from the detection data in a plurality of successivecycles.
 6. The input device according to claim 3, wherein the errordetermination unit compares a sum of the evaluation values calculatedfor the at least some of the plurality of positions with a predeterminedthreshold value, and determines whether or not an error has occurred inthe detection operation according to a result of the comparison.
 7. Theinput device according to claim 3, wherein the error determination unitcompares respective evaluation values calculated for the at least someof the plurality of positions with a predetermined threshold value, anddetermines that an error has occurred in the detection operation if anumber of positions satisfying a predetermined magnitude condition withrespect to the predetermined threshold value reaches a predeterminednumber.
 8. The input device according to claim 1, wherein the errordetermination unit is further configured to calculate, for at least someof the plurality of positions; a first evaluation value based on adifference between the detection data at a first position among the atleast some of the plurality of positions and the detection data at asecond position adjacent to the first position in each cycle; and asecond evaluation value based on a temporal change in the detection datain two successive cycles of the detection operation, and determines thatan error has occurred in the detection operation if the first evaluationvalue and the second evaluation value satisfy a predetermined errordetermination condition.
 9. The input device according to claim 8,wherein the error determination unit determines whether or not an errorhas occurred in the detection operation based on a result of comparing asum of the first evaluation values calculated for the at least some ofthe plurality of positions with a first threshold value, and a result ofcomparing a sum of the second evaluation values calculated for the atleast some of the plurality of positions with a second threshold value.10. The input device according to claim 8, wherein the errordetermination unit determines that an error has occurred in thedetection operation if (a) a first number of positions for which thefirst evaluation value of the detection data satisfies a predeterminedmagnitude condition with respect to the first threshold value reaches afirst predetermined number, if (b) a second number of positions forwhich the second evaluation value of the detection data satisfies apredetermined magnitude condition with respect to the second thresholdvalue reaches a second predetermined number, or if (c) both of the firstnumber and the second number reach the first and second predeterminednumbers, respectively.
 11. A method for controlling an input deviceexecuted by a computer, the input device including a detection surfaceto which an object approaches, and a sensor unit which detects a degreeof approach of the object to the detection surface at a plurality ofpositions thereof and generates detection data indicating a result ofthe detection for each of the plurality of positions, the methodcomprising the steps of: controlling the sensor unit such that thesensor unit periodically performs a detection operation once in eachcycle to generate the detection data for the plurality of positions;acquiring once in each cycle the detection data for the plurality ofpositions generated in the detection operation; and determining, in eachcycle, whether or not an error has occurred in the detection operationdue to noise based on a degree of a temporal change and a degree of apositional change in the detection data, wherein the step of acquiringthe detection data is skipped for a current cycle if the step ofdetermining determines that an error has occurred in the detectionoperation in the current cycle.
 12. The method of controlling an inputdevice according to claim 11, wherein the step of determining includes:calculating an evaluation value according to a degree of a positionalchange in the degree of the temporal change in the detection data ineach cycle; and determining that an error has occurred in the detectionoperation if the calculated evaluation value satisfies a predeterminederror determination condition.
 13. The method of controlling an inputdevice according to claim 12, wherein the step of determining includes:calculating, for at least some of the plurality of positions, theevaluation value based on the positional change obtained from adifference between the temporal change in the detection data at a firstposition among the at least some of the plurality of positions and thetemporal change in the detection data at a second position adjacent tothe first position, the temporal change being obtained from thedetection data in a plurality of successive cycles.
 14. The method ofcontrolling an input device according to claim 11, wherein the step ofdetermining includes: calculating an evaluation value according to adegree of a temporal change in the degree of the positional change inthe detection data in each cycle; and determining that an error hasoccurred in the detection operation if the calculated evaluation valuesatisfies a predetermined error determination condition.
 15. The methodof controlling an input device according to claim 14, wherein the stepof determining includes: calculating, for at least some of the pluralityof positions, the evaluation value based on the temporal change in adifference between the detection data at a first position among the atleast some of the plurality of positions and the detection data a secondposition adjacent to the first position among the at least some of theplurality of positions, the temporal change being obtained from thedetection data in a plurality of successive cycles.
 16. The method ofcontrolling an input device according to claim 13, wherein the step ofdetermining includes: comparing a sum of the evaluation valuescalculated for the at least some of the plurality of positions with apredetermined threshold value; and determining whether or not an errorhas occurred in the detection operation according to a result of thecomparison.
 17. The method of controlling an input device according toclaim 13, wherein the step of determining includes: comparing respectiveevaluation values calculated for the at least some of the plurality ofpositions with a predetermined threshold value; and determining that anerror has occurred in the detection operation if a number of positionssatisfying a predetermined magnitude condition with respect to thepredetermined threshold value reaches a predetermined number.
 18. Themethod of controlling an input device according to claim 11, wherein thestep of determining includes: calculating, for at least some of theplurality of positions, (a) a first evaluation value based on adifference between the detection data at a one position among the atleast some of the plurality of positions and the detection data at asecond position adjacent to the first position in each cycle, and (b) asecond evaluation value based on a temporal change in the detection datain two successive cycles of the detection operation; and determiningthat an error has been occurred in the detection operation if the firstevaluation value and the second evaluation value satisfy a predeterminederror determination condition.
 19. (canceled)
 20. The input deviceaccording to claim 1, further comprising: a storage unit configured tostore the detection data in the current cycle and the detection data ina previous cycle as input data, and to store output data to be furtherprocessed, wherein the detection data acquisition unit updates theoutput data with the input data in the current cycle if no error hasoccurred in the current cycle, while the input data in the previouscycle is maintained as the output data if an error has occurred in thecurrent cycle whereby skipping the process of acquiring the detectiondata for the current cycle.
 21. The method of controlling an inputdevice according to claim 11, further comprising: storing the detectiondata in the current cycle and the detection data in a previous cycle asinput data, and storing output data to be further processed, updatingthe output data with the input data in the current cycle if no error hasoccurred in the current cycle; and maintaining the input data in theprevious cycle as the output data if an error has occurred in thecurrent cycle whereby skipping the step of acquiring the detection datafor the current cycle.